Aristo 100 ton hopper & Kadees  - and more!

Aristo 100 Ton Hopper & Body Mount Kadee Couplers - and more!
Ted Doskaris

Sept. 20, 2010, Revision GE-B

Oct. 10, 2010, Revision GE-C

Dec. 16, 2018, Revision GE-D, Added Appendix B, 3-D printed coupler box option

Sept. 2, 2020, Revision GE-E, Added table of contents; Added Appendix C - optional coal load; Added Appendix D - replacing Aristo Trucks with Kadee's trucks




Coupler Box, Coupler & Choices
Kadee 906 Assembly Choice
Fabricating "J" Clip
A Missing Foot Stirrup!
Pictures of Car - with Kadee 906s
Operation on Layout - with Kadee 906s
Appendix A, Fabricated shim for 906s
Appendix B, 3-D Printed CamPac BoxTM Choice
Appendix C, Coal Load Option
Appendix D, Replacing Aristo Trucks with Kadee's Trucks

Where to get 3-D Printed Coupler Boxes


First, An Advisory

  • Aristo-Craft 100 ton hopper cars fitted with body mount Kadee centerset (no offset) couplers described in this vignette are intended to operate on 8 foot diameter track curves or greater.
  • Aristo 100 ton hopper cars were factory made with either plastic or metal wheels at different times. The car examples described, herein, are fitted with Aristo-Craft, ART-29111n, type metal wheels that have a smaller tread diameter than plastic wheels. As such, this affects body mounted coupler height alignment when using a Kadee 880/980 gauge. Accordingly, a car fitted with plastic wheels or other aftermarket metal wheels, may need slightly different coupler box shimming than specified in this vignette.

Coupler Box, Coupler & Choices

The Kadee "New Generation" model 906 assembly with its model 900 coupler replicates the prototype AAR type E coupler.  Since the Kadee G scale coupler assembly models 830 and 930 employ common draft gear coupler boxes with the model 906, the information presented in this vignette when using these is equally applicable.

As an alternative choice, a direct fit 3-D printed box has been developed that can be employed and will be made available for anyone interested. (See "Where to get 3-D Printed Coupler Boxes" at the end of this vignette.) This 3-D printed box is to be fitted with the coupler, springs and lid from a Kadee 907 assembly, but uses the same inline mounting hole spacing as the larger Kadee 830/906 box, thus, it is less bulky having a smaller footprint.

An example car equipped with the 3-D printed box is illustrated below.

See Appendix B for a description about the 3-D printed box and application / Go to Where to get 3-D Printed Coupler Boxes.



Kadee 906 Assembly Choice


This choice uses discrete parts (spacer & fabricated clip) to mount the Kadee 906 assembly on the car. The clip is required to anchor the flexible, and often times misaligned floor, to the end sill of the car, thereby, enabling coupler alignment with the Kadee 980 coupler height gauge.

For the Kadee 906 an Aristo-Craft Rock Island 100 ton hopper car will be used as an example. It is shown below having Kadee 906 coupler assemblies installed. 

Car Floor Preparation:

Assure all 4 screws located along the bottom spine of the car are tight. I found some of Aristo's 100 ton hopper car floor screws to be loose when I received the cars.

Two holes centered in the floor strip for mounting the Kadee coupler box via its inline holes are to be drilled and tapped  for no. 2-56 screws. The screws come with the Kadee coupler assemblies - though one longer screw will be needed as discussed later.

The hole nearest the outboard end of the car should be 0.250 inch as measured from the seam line as shown below.

The inboard hole is to be located 0.850 inch from the outboard hole so as to match the Kadee coupler box hole spacing.

A pin vise can be used for drilling the holes for the no. 2-56 screw as shown below.

Then use the tap for threading the holes for the no. 2-56 screws.


Fabricating "J" Clip - floor retaining "J" clip:

The reason for fabricating a "J" clip is to assure proper floor alignment with the car's end by attaching the car's projecting plastic floor strips to the end sills of the car. This also serves to prevent flexing of the floor strip when operating the car in long, heavy trains - particularly significant for the non brake wheel end of the car whose strip is flat and measures about 0.100 inch thick.
The brake wheel end of the car's plastic floor strip includes a molded-in brake valve assembly that dictates where the coupler box mounting screw hole locations are best placed; thus, the "J" clip clearance holes (discussed later) for the screws are positioned to correspond, accordingly.

I chose to place the threaded screw hole locations on the car floor so that they are about equally spaced on either side of the brake apparatus - straddling these protrusions with the underside shown below.

The top side of the brake apparatus as seen below is with the screws showing.

The screw locations result in the coupler box face being spaced from the end of the car by approximately 1/4 inch. In this regard, I used the same spacing for the simpler, non brake wheel end of the car for consistency.

With consideration given to realistic appearances, I examined various pictures of prototype 100 ton hopper cars, and they show the face of the coupler draft gear boxes to vary more-or-less as to how far the boxes project from the car's end (but not as much as a "Hydra Cushion" or "Shock Control" type car) - so the quarter inch, or so, scaled space of the model here is reasonably prototypical.

To jump ahead a bit, the picture below shows the mounted Kadee coupler box projection:

"J" Clip Dimensional Drawing:

Shown below is a drawing of the floor "J" clip.

"J" Clip Installation
The following pictures depict the "J" clip:

Note the inside spacing at the "J" is to be 0.210 inch. This is so it fits snugly as it wraps around the end of the car.

The long leg of the "J" clip also provides some of the shim height needed to properly space the coupler. (The Kadee coupler box assembly will need to be spaced a total of about 0.160 inches in order for the car to have the coupler align to the correct coupler height of the Kadee 880 reference gauge.)

For making the "J" clip, I purchased a sheet of 0.032 inch thick aluminum from Orchard Supply Hardware and cut and bent the pieces that were sheared from the sheet. The aluminum is easy to bend and drill as shown for the one to follow:

The "J" clip width should be from 0.500 inch to 0.525 inch max. as shown below.

The clip needs to have two 1/8 inch diameter clearance holes drilled so the no. 2-56 coupler box mounting screws will pass through without interference.
The "J" clip length should be about 1.35 inch as measured from the inside of the "J" end.

The first hole should be placed 0.425 inch from the inside edge of J part of the clip, and the second hole is to be located 0.850 inch from the first hole so it matches the hole spacing of the Kadee box.

After completing the clip, push it on the end of the car so it is seated all the way in.
(If the clip is made correctly, it should have a snug fit. A few taps from a plastic mallet will assure it is fully seated.)

After seating the clip, the drilled and tapped holes in the car floor should be viewable through the clip's larger clearance holes.  The clip's long leg may be sprung upward a bit, but when the coupler box is installed with shim/s and screwed down it will flatten out being it is made of soft aluminum.

Kadee Coupler Box Preparation & Car Mounting:

Assemble all the parts into the Kadee  boxes. The Kadee 830, 930, and 906 use the same coupler box. If desired, the exposed areas of the "J" clip, mounting shims and coupler boxes can be pre-painted to match the car before installation.

In order for the Aristo 100 ton hopper car to best assure drag-free operation on 10 foot diameter curves (and also operate on tighter 8 foot diameter curves), the boxes' side mount hole areas must be beveled trimmed (or removed) to allow the truck to pivot more fully.
As shown below, a file can be used to put an angular bevel on both sides of the coupler boxes.

The Kadee assembly can be held in a small vise whilst filing a bevel.

The coupler box assemblies can be mounted using two Kadee 841, 1/16 inch shims sandwiched between the box and the car floor "J" clip. 
(Alternatively, a singular 1/8 inch thick shim can be fabricated and used. See Appendix A for a description of this.)

When mounting the boxes to the car, all but one of the Kadee supplied no. 2-56 stainless steel 0.700 inch long screws can be used. The exception is that a longer 0.900 inch screw is needed at the brake wheel end of the car for the rear of the coupler box. So a longer screw will have to be obtained.

Preparing the Car's Barber Trucks & Installation:

The Aristo emulated roller bearing Barber trucks used on the 100 ton hopper must have their coupler tangs removed so the installed trucks won't interfere with the Kadee coupler boxes. (Unlike some cars, a truck cannot be mounted 180 degrees with coupler removed as the tang, in this case, will interfere with the car's dump bay.)
As shown below, having removed the original Aristo knuckle coupler, a razor saw can be used to cut off the tang without needing to disassemble the truck.

The trucks can then be installed on the car.

As shown below, note how the coupler box beveled areas allow a truck to pivot just enough more to facilitate car operation on an 8 foot diameter curve track.

Coupler Height Alignment with Kadee 880 / 980 Reference Gauge:

Note that Kadee markets a "New Generation" AAR Type E model 980 coupler height gauge intended for use with the newer Kadee 900, etc. type couplers.  It appears to be the same as the model 880 gauge but for having the newer 906 assembly installed. The horizontal molded seam line of the older and newer type couplers appears traverse the centers of both types, so using the 880 gauge to judge the newer coupler type's height can be done.

Shown below is the non brake wheel end of the Aristo Rock Island 100 ton hopper car.
The Kadee 906 coupler's horizontal seam line lines up perfectly with the Kadee 880 gauge coupler's seam line.

A very close coupler alignment for the brake wheel end of the car is shown below.

Again, the viewable areas of the "J" clip, spacers, and coupler box can be pre-painted prior to installation to match the car's color so as to appear more integral with the car.

In the event the coupler alignment is a bit lower than is should be, a small adjustment can be done by using a piece of tape (or very thin shim) placed near the rear of the coupler box as shown below.

In most case, I found I did not need to tweak the coupler boxes for coupler height alignment.


A Missing Foot Stirrup - nothing to do with the Kadee couplers:

I know the black foot stirrup of the example car will noticed and wondered about!

As can be seen in some prior pictures, I received this particular car with a missing foot stirrup - apparently it having been broken off and lost. Since this was the last Rock Island car left, I did not want to return it, so I decided to try and fabricate a replacement stirrup from scratch by tracing a mirror image on a sheet of plastic backed with some painters tape. (It is my first attempt to do something like this.)

I  CA glued the finished part in place.

It will need to be painted. Hopefully, the part will stay put; it seems sturdy enough, but should it come off that is time it can be trimmed to look better.

Pictures of the Car - with Installed Kadee 906 Couplers:

Shown below is an end view of the car depicting the end of the "J" clip, the Kadee 841 1/16 inch spacers, and the coupler box with its coupler.

Note how the new Kadee 901 type coupler brass spring is no longer exposed but now installed within the interior of the coupler's mechanism.

The brake assembly end of the car can be seen below.

Shown below is the Aristo black "Club Car" of year 2001 coupled to the Rock Island car on the right - both having the Kadee 906 coupler assemblies installed.

Shown below is a side view of the completed car.

Comparison of Car Spacing  - Aristo Couplers vs. Kadees:

With two Aristo 100 ton hopper cars coupled together, the distance between them is observed.

As shown below, the original truck mounted coupled cars with Aristo knuckle couplers measured 2.1 inches apart.

As shown below, the body mounted Kadee 906 coupled cars measured 1.6 inches apart in their relaxed state. (The Kadee model 906 coupler - as do the 830 and 930- include a spring within the coupler box that allows the coupler to extend with tension applied.)

As shown below, the body mounted Kadee 906 coupled cars measured 1.9 inches apart with tension applied so that the cars were spread apart as far as they could be.

Thus, the cars are closer together with the Kadee body mount couplers than with the original Aristo arrangement by 0.2 inch with fully tensioned Kadees. During train operation (being load dependant) this would be the worst case condition.


Operation on Layout - with Kadee 906s:

The Aristo Rock Island 100 ton hopper example car with Kadee 906 coupler assemblies installed as described and previously shown operated flawlessly on my circuitous under house layout comprised of mostly 10 foot diameter curves. The car was placed on the front of a 61 car train pulled by two Aristo GP40s and one SD45 - it being coupled to the Aristo SD45.

Shown below is the Rock Island 100 ton hopper "Kadee coupled" to the trailing SD45.

Shown below is an overhead view of the car with body mount Kadee 906 as coupled to the SD45 having body mount Kadee 789 center set coupler (in a modified coupler box).
The car's coupler attitude could not be more ideal.

Shown below is the inside curve track view of the horizontal attitude of the coupled car with the SD45.
There is some vertical misalignment with the loco - not unexpected given the load of the 62 car train on the layout's circuitous, mostly 10 foot diameter, curved trackage.
The car never came uncoupled or indicated it would "string-line" whilst traversing around the 270 degree loop-back as depicted.

Show below is the other side of the car as seen on the outside of the 10 foot diameter loop-back curve:


Appendix A - Fabricated shim (coupler box spacer):

As an alternative to using Kadee 841 factory made shims (two 1/16 inch shims stacked), a singe 1/8 inch thick spacer is preferable.

For material used for making spacers, a 1 inch wide strip of 1/8 inch thick black plastic strip can be purchased from Tap Plastics at an inexpensive price.

The spacer should be 1 inch wide (the width of the Kadee coupler box) by 1.5 inches long (minimum) as shown below.

A Kadee coupler box assy. (or AML brand assy.) can be used as a jig for drilling the holes in the spacer by putting the spacer under the assembly with it fully butted against the coupler box lid's lip as shown below.

I used a 7/64 inch drill which is slightly smaller than the coupler box holes.

Before starting the drill, plunge the drill bit part way down into the coupler box hole (as shown below) so as to avoid the risk of nicking away material from the box.

The results can be seen below.

Shown below is the fabricated spacer temporarily installed on the Kadee 906 coupler assembly along with the "J" clip.

Note the longer screw (0.9 inch) at the rear of the coupler box as shown is intended for mounting this assembly on the brake wheel end of the car. All other mounting screws used are the Kadee supplied 0.7 inch long screws. (The other end of the car uses the Kadee supplied screws for both coupler box mounting holes.)

If obtaining long 2-56 screws proves to be difficult, black 2-56 X 1 inch long button head screws can be purchased from Carpenter Creek, Inc. located in Woodstock, Georgia.  I used these screws on subsequent cars I worked on and found them to be very realistic in appearance.

Shown below is the "J" clip, coupler box and singular fabricated 1/8 inch thick spacer mounted to the car.

Shown below is the brake wheel end of the car with all items installed.

Note I had painted the end of the "J" clip similar to the car so it would not be too noticeable.

Appendix B, Using the 3-D Printed CamPac BoxTM.

This choice uses a direct fit 3-D printed coupler box assembly, when installed, that obviates the need for a spacer whilst intrinsically aligning the car floor to the end sill preventing flex, thereby, enabling coupler alignment with the Kadee 980 coupler height gauge.

This choice uses the coupler, springs and lid from the Kadee 907 kit to be installed in the CamPac coupler box that has a more realistic smaller "foot print" than the Kadee 906.

A couple of Aristo-Craft Southern Pacific 100 ton hopper cars that resemble the prototype will be used as an example.


The CamPac Box can be painted before being mounted as shown below in the summary illustration that reveals how all will look when completed.

Comment: Compared to using a Kadee 830/906 box, the truck can be rotated to a greater degree before making physical contact against the smaller foot print CamPac Box. This is beneficial for car operation on tight curves.


The coupler box projection from the end sill is about 0.400 inch when scaled up at almost 1 foot is like some, but not all, prototype 100 ton hopper cars.



CamPac Box & Preparation

The 3-D printed box can be made from black or gray resin.


As illustrated below, the box is to be fitted with parts from a Kadee 907 kit that the user must obtain.


Like a discretely mounted Kadee 830/906 box requiring a "J" clip when mounting (needed to align & stabilize chassis floor), the CamPac Box integrates this feature along with virtual shimming that affords a direct fit to the car.



Preparing Car Chassis Mounting Holes

The hole locations are the same as was done for the discretely mounted Kadee 906 box using its two in-line holes. In this regard, a car fitted with the Kadee 906 as with the previously described Rock Island car can be refitted with a CamPac Box.

Illustrated below are the locations of the mounting holes.

With trucks removed, two holes are to be located & drilled the same at A & B end of the chassis.
For #2-56 machine screws, use #51 drill & tap holes - the preferable screw choice.
For Kadee #4 self threading screws, use #44 drill - less desirable choice because of larger screw bulk

To make locating the holes easier, the CamPac Box can be used as a template as illustrated below.

For more accuracy, particularly with the pad recess at the "B end" of the car, it's preferable to mark the hole locations first, then remove the CamPac Box to check the hole locations with respect to the dimensions (correct as needed), and finally drill the holes. This technique is Illustrated below.


Mounting Screw Choices

Two screw sizes to consider include the following:

(1) Kadee #4 self threading screws from the Kadee 907 kit. These coarse thread screws are less desirable because of their larger bulk and pointed ends which is very noticeable - illustrated below:


(2) #2-56 machine screws. These are the preferable screw choice, though a tap should be used to thread holes.
The #2-56 screws needed for the car "B end" are shown below, including how they would appear on the car.


The #2-56 screws needed for the "A end" are shown below, including how they would appear on the car.


Fastening the CamPac Box

The box is fastened to the each end of the car in the same way. Note a shim from the Kadee 907 kit's capsule may be needed to be placed on the chin of the box "J lip" to eliminate vertical slack, if present - Illustrated below

Remounting the Trucks

When remounting Aristo trucks having factory knuckle couplers, the tang with coupler must be cut off near its "T" intersection of the bolster just as done when body mounting the Kadee 906 coupler assemblies. Only removing the coupler from the tang and turning the truck 180 degrees won't work because the tang will interfere with the car's dump bay.


Coupler alignment results on the two example cars were the same.

Both ends of an example car are illustrated below.


The "B end":


The "A end":


Comment: Available is two sheet PDF file, "Aristo 100 Ton Hopper CamPac BoxTM Quick Install Guide"


Appendix C, Coal Load Option

Aristo-Craft had offered an optional coal load, ART-60407, made of molded foam that weighs a quarter pound.


The coal load is to be pressed into the top of the car.


The before & after weight with coal load is shown below.



Appendix D, Replacing Aristo Trucks with Kadee's Trucks

Some of the 100 ton hopper cars came with plastic wheels. Replacing the factory wheels with metal wheels is much preferred, but availability of Aristo's wheels intended for the "roller bearing" trucks (P/N ART-29111D) can be difficult to obtain. Likewise for other substitute wheels that could fit or may be adapted to fit. Given this, one solution is to replace the Aristo trucks with aftermarket Kadee "roller bearing" type trucks - to be described.

Whilst the Kadee #974 "100 ton" truck would seem the most likely replacement, it's a bit too big having larger diameter wheels that present operation problems; hence, the practical choice is the smaller Kadee #973 "70 ton" truck, being close in wheel base size with wheel diameters of the Aristo 100 ton truck. A comparison of these trucks is Illustrated below.


Illustrated below is the Aristo 100 ton hopper car fitted with Kadee #973 "70 ton" trucks:


With body mount couplers, it's important to keep this car's height from the railhead the same as the factory height so the couplers will still align with the Kadee coupler height gauge, but doing so requires some ingenuity when using the Kadee trucks. Accordingly, the parts from Kadee's adapter kit to be used will be parts intended for the USA Trains, not Aristo-Craft - illustrated below.

The alternate metric truck mounting screw is shown below.


Before mounting the trucks, the adapter kit's "hat" must first be temporarily pre fit & seated on the car's bolster posts, then removed; otherwise during truck installation the plate could pop up and get stuck in any latent gap under the hat - illustrated below.


Now the trucks can be installed following the sequence illustrated below.


Examining the mounted trucks' wheel clearance on 8 foot diameter track with the car upside down shows plenty of clearance with the small foot print CamPac BoxTM.


And the couplers still align with the Kadee gauge:


The car's weight with Kadee #973 trucks is shown below.



Video - operation of cars outdoor layout:

Aristo SP Dash 9 Coal Train on Layout
(Includes hopper cars with Kadee 906s and 3-D printed boxes fitted with couplers from Kadee 907 kit)



Where to get 3-D Printed Coupler Boxes

The direct fit coupler box for the Aristo 100 ton hopper car is designed by me (Ted Doskaris) in conjunction with Colin Camarillo who has the 3-D printer, along with supporting apparatus & software etc. expertise, to implement the design. If interested in acquiring these boxes, visit Colin's Web site CamPac BoxTM page.





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